Transducer support apparatus



May 26, 1964 M. E. DEMPSEY ETAL 3,134,361

TRANSDUCER SUPPORT APPARATUS Filed April 16, 1962 ATTORNEYS.

United States Patent 3,134,861 TRANSDUCER SUIPGRT APPARATUS Martin E. Dempsey, Mount Prospect, and Edward B. Michal, Chicago, Ill., assignors to Beltone Electronics Corporation, a corporation of Illinois Filed Apr. 16, 1962, Ser. No. 187,663 9 Claims. (Cl. 179-156) This invention relates in general to improved arrangements for mounting vibratory transducer apparatus of the type used in audiometric testing, and more particularly to a unique headband mounting arrangement for a transducer capable of inducing masking or other audio signals in the forehead of the wearer with very little transmission of audio signals through the headband or through an air path to the ears.

Those skilled in the audiometric arts are aware of the problems present in conducting hearing tests in that a test conducted for one ear may involve the undesirable transmission of audio signals through the bone structure of the skull or through an air path to the other ear. The result is that the other ear may receive such unwanted audio transmissions and the test will not be an accurate or reliable measure of any hearing loss in the ear being tested. One attempted remedy for this problem has been the introduction of masking signals into the bone structure and this is usually effected by placing large amplitudes of audio signal vibrations into the forehead, which vibrations serve to mask the audio signals which are simultaneously put into one-or both ears. This procedure commonly is known as a Rainville test. In the prior art, the head bands or straps which have been used for supporting the masking signal transducer have had the undesirable tendency of picking up the audio vibrations of the transducer and transmitting them to the head as well as supporting the transducer with variable force due to variations in head size and band tightness. Those skilled in the art will appreciate that in order for the transducer to operate properly, it must be held against the forehead with a realtively constant force.

The present invention, therefore, is directed to a new and improved arrangement for acoustically and mechanically isolating the head band or strap from the vibratory transducer while at the same time securely maintaining the transducer against the forehead with relatively constant force to enable the masking signals to be introduced at the midpoint of the skull.

It is therefore, a principal object of this invention to provide an improved mounting and supporting arrangement for a vibratory electroacoustic transducer of the type used in audiometric testing applications.

It is another object of this invention to provide a unique head band construction for securely maintaining a bone conduction receiver against the forehead of the wearer during audiometric testing which provides effective isolation against undesired acoustic and mechanical transmission to the other parts of the head.

It is a further object of this invention to provide such an improved transducer support and mounting arrangement as above, which is characterized by its relative efliciency, its light weight, and its acoustic and mechanical isolation properties.

It is a still further object of this invention to provide a transducer support and mounting arrangement which serves to hold the transducer against the forehead with relatively constant force, regardless of variations in head size.

The novel features which are characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood 3,134,861 Patented May 26, 1964 by reference to the following description taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a general perspective view of the improved bone conduction transducer support and mounting strap combination;

FIGURE 2 is a perspective view showing the interior of the transducer support and mounting assembly;

FIGURE 3 is an exploded perspective view of the transducer support mounting assembly;

FIGURE 4 is a pictorial view illustrating the invention as worn on the forehead of the patient during an audiometric test;

FIGURE 5 is a sectional view taken substantially as shown along the line 55 of FIGURE 2; and

FIGURE 6 is a sectional View taken substantially as shown along the line 6-6 of FIGURE 5.

Referring now to the drawing, and more particularly to FIGURE 1 thereof, one illustrative embodiment of the transducer support invention is indicated by the reference character 10. Advantageously, it comprises a flexible band or strap 12 having suitable buckling elements 14 and 16 at opposite ends thereof, which together with an adjustment element 17, permit the strap to be adjustably and snugly engaged about the head 18 of the patient, as seen in FIGURE 4.

A transducer support and mounting assembly 20 is carried by the strap 12 and is adapted to normally rest against the center of the forehead, as seen in FIGURE 4. The support and mounting assembly 20 comprises a cupshaped housing 24, a viscoelastic acoustic seal 22, a headband retaining element 26, and an electroacoustic transducer 27. The housing or shell 24 is carried on the strap 12 by means of the retaining element '26.

Preferably, the retaining element 26 is generally U- shaped and has a guide way 28 in its base leg for receiving the strap 12, while the ends of its side legs 29 are fastened to the top and bottom walls of the shell 24. The perimeter edges of the shell 24 is provided with a flange 30 that serves to engage with a corresponding groove in the viscoelastic seal 22 so that the seal effectively serves as a buffer or acoustic isolator between the shell 24 and the head 18.

The shell 24 advantageously is provided with a resilient filler 32, such as closed cell, foam rubber for example,

which rests against the back wall of the shell. The filler 32 is provided with a central aperture or recess 36 in which a hollow, air filled, resilient bone conduction transducer mount, or vibration isolator block 38 is supported. The transducer mount 38 is supported against the back wall of the shell. In accordance with a feature of this invention, it is generally rectangular in shape and has a central concave opening defined by a plurality of upstanding walls against the edges of which is mounted a bracket 40. The bracket 40 has a pair of projecting arms 42 midway along its top and bottom edges and each arm carries a pin 44 projecting inwardly and towards the other arm. The pins 44 are adapted to be engaged in respective socket members 46 provided on opposite side walls of the vibratory electroacoustic transducer 27.

The electroacoustic transducer 27 is of conventional design, well known to those skilled in the art and has extending therefrom a pair of electric signal conductors 48 and 50 through which electrical connections are provided for vibrating the transducer against the forehead of the patient. The conductors 48 and 50 extend through a rubber grommet 52 provided in one side wall of the shell 24 and terminate in a plug member 54 of conventional design for connection to a suitable audiometer instrument capable of providing masking and other acoustic signals.

In the operation of the invention, the assembly 10 is mounted on the wearers head by simply placing the assembly 20 against the midpoint of the forehead with the transducer 27 and the seal 22 in secure engagement with the forehead. The belt or strap 12 is wrapped about the head and adjusted as needed to bring the transducer seal 22 into engagement with the head as the strap 12 passes against the shell 24 which, in turn, firmly holds the transducer 27 in position. It is of particular importance, for both acoustical isolation and proper force of transducer 27 against the forehead, that the belt or strap 12 be adjusted snug enough so'that the seal 22, as well as transducer 27 are in contact with the forehead.

Electrical circuits are extended into the transducer through conductors 48 and 50 to cause the desired masking signals to be introduced into the head in the proper position. It now will be fully appreciated by those skilled in the art that due to the unique construction of the transducer support and mounting assembly of this invention, such masking signals are effectively isolated against undesirable transmission to other parts of the head with the hollow air filled vibration isolator transducer mount 38 and resilient filler 32 serving to isolate mechanical vibrations and with the viscoelastic seal 22 serving to block audio transmissions through air as well as mechanical paths.

It further will be appreciated that the transducer is held against the forehead with a relatively constant amount of force despite variations in head size. When the transducer mount is pressed against the forehead, the transducer 27 and resilient seal 22 around the edge of the housing 24 are in contact with the forehead. Since the transducer normally protrudes beyond resilient seal 22, it will be pushed into the housing 24 a fixed distance. At the same time, the vibration block isolator 38 will be compressed this same distance, pushing the transducer against the forehead with a constant, fixed force. Small variations in this force may occur due to variations in the forehead contour.

While there has been shown and described a specific embodiment of the present invention, it will, of course, be understood that various modifications and alternative constructions may be made without departing from the true spirit and scope of the invention. Therefore, it is intended by the appended claims to cover all such modifications and alternative constructions as fall within their true spirit and scope.

What is claimed as the invention is:

1. A transducer mounting for enabling sound waves to be introduced into the bone structure of the head at a predetermined position only, comprising the improvements of a housing, a retaining element fastened to said housing and adapted to support a flexible head encircling strap, a resilient mounting positioned within said housing, a bracket positioned on said resilient mounting and having a pair of extending arms, a pin at the end of each arm and extending inwardly therefrom, a transducer having apertures in opposite walls for receiving said pins whereby said transducer is supportingly suspended between said arms, and a resilient seal of viscoelastic material carried on the perimeter edges of said housing for engagement with said head, said viscoelastic seal engaging the head simultaneously with a vibratory wall of said transducer in response to said strap being adjusted about the head to bear against said housing.

2. A bone conduction transducer mounting for enabling sound waves to be introduced to the head at a predetermined position comprising the improvement of a flexible strap adapted to be adjustably fastened about the head, a cup-shaped housing, a retaining element fastened to said housing for supporting engagement with said strap, a vibration isolator block positioned Within said housing, a bracket carried on said vibration isolator block and having base and a pair of support arms extending therefrom, a bone conduction transducer supportingly mounted between said arms whereby said transducer is suspended between said arms at a position spaced from said bracket base and a resilient seal around the perimeter edge of said cup-shaped housing for engagement with said head, said resilient seal engaging the head simultaneously with a vibratory wall of said transducer in response to said flexible strap being adjusted about the head to bear against said housing.

3. A bone conduction transducer mounting in accordance with claim 2 wherein the volumetric dimensions of said cup-shaped housing are greater than the volumetric dimensions of said vibration isolator block, the space between the inner walls of said housing and the isolator block being filled with a resilient material, such as closed cell, foam rubber material.

4. A bone conduction transducer mounting in accordance with claim 2 wherein said vibration isolator block is formed of a resilient material, such as soft rubber.

5. A bone conduction transducer mounting in accordance with claim 2 wherein said vibration isolator block comprises a hollow, air filled member defined by a plurality of walls of resilient material.

6. A bone conduction transducer mounting in accordance with claim 2 wherein said bracket is formed of a rigid plate positioned on the edges of the resilient Walls of said isolator block to completely enclose said hollow, air-filled member.

7. A bone conduction transducer mounting in accordance with claim 2 wherein said resilient seal is formed of a visco-elastic material, such as Silastic.

8. A transducer mounting for enabling sound vibrations to be introduced into the forehead with mechanical isolation from the remainder of the head comprising the improvement of a cup-shaped housing, a flexible strap coupled to said housing and adapted to be fitted around the head, a hollow, air filled vibration isolator block within said housing, a bracket attached to said isolator block and having a pair of extending arms, means on said arms for suspending a transducer therefrom, and a viscoelastic seal positioned on the perimeter edges of said housing for resilient engagement with said head to permit the vibratory wall of said transducer to be placed in firm engagement with the forehead in response to the adjustment of said strap about the head.

9. A transducer mounting in accordance with claim 8 in which a rubber grommet is provided in one wall of said housing to permit electrical leads extending from said transducer to be resiliently carried by said housing.

No references cited. 

1. A TRANSDUCER MOUNTING FOR ENABLING SOUND WAVES TO BE INTRODUCED INTO THE BONE STRUCTURE OF THE HEAD AT A PREDETERMINED POSITION ONLY, COMPRISING THE IMPROVEMENTS OF A HOUSING, A RETAINING ELEMENT FASTENED TO SAID HOUSING AND ADAPTED TO SUPPORT A FLEXIBLE HEAD ENCIRCLING STRAP, A RESILIENT MOUNTING POSITIONED WITHIN SAID HOUSING, A BRACKET POSITIONED ON SAID RESILIENT MOUNTING AND HAVING A PAIR OF EXTENDING ARMS, A PIN AT THE END OF EACH ARM AND EXTENDING INWARDLY THEREFROM, A TRANSDUCER HAVING APERTURES IN OPPOSITE WALLS FOR RECEIVING SAID PINS WHEREBY SAID TRANSDUCER IS SUPPORTINGLY SUSPENDED BETWEEN SAID ARMS, AND A RESILIENT SEAL OF VISCOELASTIC MATERIAL CARRIED ON THE PERIMETER EDGES OF SAID HOUSING FOR ENGAGEMENT WITH SAID HEAD, SAID VISCOELASTIC SEAL ENGAGING THE HEAD SIMULTANEOUSLY WITH A VIBRATORY WALL OF SAID TRANSDUCER IN RESPONSE TO SAID STRAP BEING ADJUSTED ABOUT THE HEAD TO BEAR AGAINST SAID HOUSING. 